The present invention relates to an electronic timepiece of analog display type, provided with a plurality of function modes, e.g. a normal timekeeping mode and an alarm time mode. It should be noted that the term "analog display" as used in the present specification and the appended claims is used for brevity of description to refer to a timepiece display of conventional type having time indicating hands and a dial.
At present, electronic timepieces using a quartz crystal controlled oscillator circuit as a standard frequency signal source are in wide use. These are either of analog display type or digital display type. The analog display electronic timepiece has tended to become of very high accuracy and of slim and elegant shape. The digital display electronic timepiece, on the other hand, has increasingly tended to offer a multiplicity of function modes, e.g. an alarm mode, stopwatch mode, elapsed time mode, etc. Such function modes can be easily and conveniently provided with such digital timepieces because the liquid crystal displays generally used at present, for digital display timepieces, can be rapidly switched over from displaying one set of information to displaying some other set of information.
It would be desirable to be able to combine the attractive characteristics of an analog display electronic timepiece with a capability for immediate changeover among a plurality of different function modes, such as is possible with a digital display timepiece. However, this has not been achieved on a practical basis, up to the present, for a number of reasons. One of these reasons is due to the basic nature of the means whereby the time indicating hands of an analog display electronic timepiece are driven, i.e. by an electromechanical transducer (e.g. a stepping motor) acting through a gear train. If changeover is performed between one function mode and another, e.g. from the normal timekeeping mode in which current time is displayed to an alarm time mode in which a preset alarm time is displayed, then it is necessary to rapidly change all of the time indicating hands from one set of positions to another set of positions. This could be accomplished relatively rapidly for the seconds hand. However, because of the speed reduction provided by the wheel train of the timepiece, a relatively long time would be required for the hours and minutes hands to be changed to new positions.
The latter problem can be substantially overcome by using a plurality of electromechanical transducers to drive the hands, e.g. one stepping motor to drive the seconds hand and another to independently drive the hours and minutes hands. Such a solution would normally result in an increased drain of battery current, when all of the timekeeping hands are being simultaneously rotated to new positions, thereby requiring a larger size of timepiece battery. In addition, use of two electromechanical transducers would normally require the number of drive inverters used to drive these transducers being doubled. This is an important point, since these drive inverters substantially dictate the overall size of the integrated circuit used in an analog display electronic timepiece. However, as described in the specification, the present invention enables such problems which have arisen with prior art methods of using a plurality of electromechanical transducers to drive the hands of an analog display electronic timepiece to be substantially eliminated.
Another difficulty which arises in providing a multiple mode changeover capability with an analog display electronic timepiece lies in the problem of how to provide a positive indication to the timepiece user that changeover from one function mode to another has been accomplished. With a digital display timepiece, this can be easily implemented by means of specific symbols or markers which are activated to indicate the currently selected function mode. With an analog display electronic timepiece, however, such means are not available. This problem is overcome, with an analog display electronic timepiece according to the present invention, by causing the timepiece hands to move in a predetermined manner to indicate function mode information. For example, when change over is performed between a current time display mode and an alarm mode, the seconds hand of the timepiece can be made to go rapidly to the zero seconds position, and remain at that position. To indicate that the timepiece alarm is set to the ON state, so that an audible alarm signal will be generated, the seconds hand (or another hand) can be made to vibrate back and forth.
In addition, as described in detail hereinafter, the present invention teaches circuit means whereby, when changeover from one function mode to another is performed, information designating the new positions which the hands must take up is immediately generated, and applied to the drive circuits actuating the electromechanical transducer or transducers of the timepiece. It is an important feature of the present invention that the latter hands position information generating circuit means are extremely simple, and can easily be combined with other circuitry of the timepiece.
An analog display electronic timepiece having a plurality of function modes, according to the present invention, can therefore be easily designed and manufactured on a practical basis, and will combine the advantageous features provided by such a timepiece in the prior art with the advantages of a function mode selection capability which has hithereto been available only with digital display electronic timepieces.